A system and method for laser tracking using an optical fiber power meter

Abstract

The present invention provides a system and method for tracking and aiming laser using an optical fiber power meter, comprising a quick-reflection mirror, the mirror surface of the quick-reflection mirror reflects incident laser light to an optical fiber, an optical fiber power meter is provided on the optical fiber, the optical fiber power meter is connected to a tracking and aiming module, and the tracking and aiming module is connected to a driving circuit of the quick-reflection mirror; the optical fiber power meter is used to detect an optical signal incident on the optical fiber to obtain a power detection signal; the tracking and aiming module is used to: process the power detection signal to obtain a power detection value and select a corresponding scanning strategy, and generate a driving control signal in executing the scanning strategy to find an optimal optical fiber coupling point; the driving circuit drives the quick-reflection mirror to adjust its position according to the driving control signal, so that the mirror surface of the quick-reflection mirror points to the optimal optical fiber coupling point. The position detection device and the spectroscope are eliminated, the cost is reduced, the difficulty of installation and adjustment is reduced, the installation space is saved, and the optical power loss is reduced.

Description

Technical Field

[0001] The present invention relates to the field of space laser communication technology, and in particular to a system and method for laser tracking and aiming using an optical fiber power meter. Background Art

[0002] With the rapid development of the domestic low-altitude economic industry, the demand and application of space laser communication technology are growing. The basic principle of space laser communication is to use laser as a carrier, through free space and the atmosphere as a carrier, to achieve efficient and fast data transmission. The space laser communication system has a series of advantages such as wide bandwidth, high transmission speed, high safety performance, small equipment size, light weight, and low system power consumption. It has gradually become an emerging development industry.

[0003] The focus of space laser communication research is on the technology of pointing, acquiring and tracking (PAT). Basically, all space laser communication system terminals use PAT technology to capture and track the light spot. In the traditional implementation of capturing and tracking, it is necessary to rely on position detection devices combined with light spot positioning algorithms to solve the light spot position. Commonly used position detection components include position sensitive detectors (PSD: Position Sensitive Device), charge coupled detectors (CCD: Charge-Coupled Device), CMOS cameras (Complementary Metal Oxide Semiconductor), quadrant detectors (QD), etc.

[0004] The existing PAT technology in space laser communication needs to rely on position detection devices to detect the position of the light spot and calculate the center of mass of the light spot. In the optical-mechanical system, the received light signal needs to be split by a spectroscope and enter the position detection device. The current technology has the following three main disadvantages:

[0005] 1. The existence of the beam splitter is to decompose one path of incident light into two paths of outgoing light, which will inevitably cause a huge loss of optical power. A general beam splitter will at least lose 10% of the effective optical power, and optical power is extremely important in laser communication, especially long-distance communication.

[0006] 2. The price of position detection devices is also related to the type of use, ranging from thousands to hundreds of thousands of yuan, which increases the cost of the entire optical machine.

[0007] 3. The use of beam splitters and position detection devices will increase the design volume and assembly difficulty of the overall optical machine. Summary of the invention

[0008] Based on the above records, the present invention provides a system and method for laser tracking and aiming using a fiber optic power meter, aiming to solve technical problems such as high cost and power loss of laser aiming in the prior art.

[0009] A system for tracking and aiming lasers using an optical fiber power meter comprises a quick-reflection mirror, the mirror surface of which reflects incident laser light to an optical fiber, an optical fiber power meter is arranged on the optical fiber, the optical fiber power meter is connected to a tracking and aiming module, and the tracking and aiming module is connected to a driving circuit of the quick-reflection mirror;

[0010] The optical fiber power meter is used to detect the magnitude of the optical signal incident on the optical fiber and obtain a power detection signal;

[0011] The tracking module is used to: process the power detection signal to obtain the power detection value and select the corresponding scanning strategy, and generate a driving control signal in the execution of the scanning strategy to find the best optical fiber coupling point;

[0012] The driving circuit drives the fast-reflecting mirror to adjust its position according to the driving control signal, so that the mirror surface of the fast-reflecting mirror points to the optimal optical fiber coupling point.

[0013] Furthermore, the tracking module includes:

[0014] A first scanning submodule, used for acquiring the position of the fast reflection mirror whose power detection value is greater than a first threshold value based on a full-range spiral scanning strategy, to form a first acquisition result;

[0015] A second scanning submodule, connected to the first scanning submodule, is used to obtain the position of the fast reflection mirror whose power detection value is greater than the second threshold value based on the mid-range circular scanning strategy according to the position of the fast reflection mirror of the power detection value in the first acquisition result, to form a second acquisition result;

[0016] The third scanning submodule is connected to the second scanning submodule and the first scanning submodule respectively, and is used to obtain the best fiber coupling point based on the best approach range scanning strategy according to the position of the fast reflection mirror of the power detection value obtained in the second acquisition result.

[0017] Furthermore, the first scanning submodule includes:

[0018] A starting point updating unit, used for updating the first starting point position of the fast reflection mirror as the starting point for executing the full range spiral scanning strategy;

[0019] A first scanning unit, connected to the starting point updating unit, is used to start executing a full-range spiral scanning strategy based on the first starting point position as the starting point;

[0020] A first judgment unit, connected to the starting point updating unit and the first scanning unit, respectively, is used to judge whether there is a power detection value greater than a first threshold value when the fast reflection mirror is at the first starting point and executes the full-range spiral scanning strategy, and obtain a first judgment result;

[0021] The first scanning unit is used for:

[0022] When the first judgment result is that there is a power detection value greater than the first threshold, stop executing the full-range spiral scanning strategy, form a first acquisition result and output it to the second scanning submodule;

[0023] When the first judgment result after executing a full-range spiral scanning strategy is that there is no power detection value greater than the first threshold, a first error reporting information is generated;

[0024] The starting point updating unit is further used for updating the first starting point position of the fast reflection mirror according to the first error reporting information as the starting point for the next execution of the full-range spiral scanning strategy.

[0025] Furthermore, the second scanning submodule includes:

[0026] A second scanning unit, configured to use the position of the fast reflection mirror of the power detection value obtained in the first acquisition result as the second starting point position, and execute a medium-range circular scanning strategy;

[0027] A second judgment unit, connected to the second scanning unit, is used to judge whether a power detection value of the fast reflection mirror at the second starting point position and a power detection value in the circular scanning strategy in the executing range is greater than a second threshold value, and obtain a second judgment result;

[0028] The second scanning unit is also used for:

[0029] When the second judgment result is that there is a power detection value greater than the second threshold, stop executing the circular scanning strategy in the middle range, form a second acquisition result and output it to the third scanning submodule;

[0030] After executing a cycle of the mid-range circular scanning strategy, when no second judgment result has a power detection value greater than the second threshold, second error reporting information is generated.

[0031] Furthermore, the third scanning submodule includes:

[0032] A third scanning unit is used to use the position of the fast reflection mirror of the power detection value obtained in the second acquisition result as the third starting point position, execute the best approach range scanning strategy, and obtain the best optical fiber coupling point;

[0033] A third judgment unit, connected to the third scanning unit, is used to judge whether the detected power detection value drops to no more than the first threshold value when the fast reflection mirror points to the optimal optical fiber coupling point, and obtain a third judgment result;

[0034] The third scanning unit is also used for:

[0035] When the third judgment result is that the power detection value is not greater than the first threshold, third error reporting information is generated;

[0036] When the third judgment result is that the power detection value is greater than the first threshold, the best approach range scanning strategy continues to be executed.

[0037] A method for tracking and aiming a laser using an optical fiber power meter, using the aforementioned system for tracking and aiming a laser using an optical fiber power meter, comprising:

[0038] Step A1, the mirror surface of the fast reflection mirror reflects the incident laser to the optical fiber, and the optical fiber power meter on the optical fiber detects the optical signal incident to the optical fiber to obtain the size of the power detection signal;

[0039] Step A2, processing the power detection signal to obtain a power detection value;

[0040] Step A3, selecting a corresponding scanning strategy based on the power detection value, and generating a driving control signal in executing the scanning strategy to find the best optical fiber coupling point;

[0041] Step A4, driving the fast reflection mirror to adjust its position according to the driving control signal, so that the mirror surface of the fast reflection mirror points to the optimal optical fiber coupling point.

[0042] Furthermore, step A3 includes:

[0043] Step A31, based on a full-range spiral scanning strategy, obtaining the position of the fast reflection mirror whose power detection value is greater than a first threshold, to form a first acquisition result;

[0044] Step A32, according to the position of the fast reflection mirror of the power detection value in the first acquisition result, based on the circular scanning strategy in the middle range, the position of the fast reflection mirror with a power detection value greater than the second threshold is acquired to form a second acquisition result;

[0045] Step A33, according to the position of the fast reflection mirror of the power detection value obtained in the second acquisition result, the best fiber coupling point is obtained based on the best approach range scanning strategy.

[0046] Further, step A31 includes:

[0047] Step A311, updating the starting point of the fast reflection mirror as the first starting point position for executing the full range spiral scanning strategy;

[0048] Step A312, determining whether the power detection value obtained by the fast reflection mirror at the first starting point is greater than a first threshold:

[0049] If not, execute step A313;

[0050] If yes, execute step A315;

[0051] Step A313, based on the first starting point position as the starting point, start to execute the full-range spiral scanning strategy, and determine whether there is a power detection value greater than the first threshold value in the execution of the full-range spiral scanning strategy:

[0052] If not, execute step A314;

[0053] If yes, execute step A315;

[0054] Step A314, after executing a full-range spiral scanning strategy, generating first error reporting information, and continuing to step A311;

[0055] Step A315, stop executing the full-range spiral scanning strategy, form and output the first acquisition result, and then execute step A32.

[0056] Further, step A32 includes:

[0057] Step A321, taking the position of the fast mirror of the power detection value obtained in the first acquisition result as the second starting point position, and determining whether the power detection value of the fast mirror at the second starting point position is greater than a second threshold:

[0058] If not, execute step A322;

[0059] If yes, execute step A324;

[0060] Step A322: Execute the circular scanning strategy in the middle range from the second starting point as the starting point, and determine whether there is a power detection value greater than the second threshold value in the circular scanning strategy in the middle range:

[0061] If not, execute step A323;

[0062] If yes, execute step A324;

[0063] Step A323, after executing a cycle of the mid-range circular scanning strategy, second error reporting information is generated, and then step A31 is executed;

[0064] Step A324, stop executing the circular scanning strategy in the middle range, form and output the second acquisition result, and then execute step A33.

[0065] Further, step A33 includes:

[0066] Step A331, taking the position of the fast reflection mirror of the power detection value obtained in the second acquisition result as the third starting point position, executing the best approach range scanning strategy to find the best fiber coupling point;

[0067] Step A332, when the fast reflection mirror points to the best fiber coupling point, if it is detected that the power detection value decreases but is greater than the first threshold, continue to execute the best approach range scanning strategy; if it is detected that the power detection value decreases and is not greater than the first threshold, execute step A333;

[0068] Step A333, forming third error reporting information, and then executing step A31.

[0069] The beneficial technical effect of the present invention is that the present invention sets a fiber optic power meter directly on the optical fiber receiving the laser, thereby aiming according to the detection signal and scanning strategy fed back by the fiber optic power meter, eliminating the position detection device and the spectrometer, reducing the cost of use, reducing the difficulty of installation and adjustment, and saving installation space. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 , Figure 3-Figure 6 A schematic diagram of a module of a system for laser tracking and aiming using an optical fiber power meter according to the present invention;

[0071] Figure 2 A simple schematic diagram of the optical path of a system for laser tracking and aiming using an optical fiber power meter according to the present invention;

[0072] Figure 7-Figure 11 A flowchart of the steps of a method for laser tracking and aiming using an optical fiber power meter according to the present invention;

[0073] Figure 12-14 It is the simulation diagram of equal angular velocity under different configuration parameters of the full range spiral scanning strategy;

[0074] Fig.15 The simulation diagram of equal linear speed under one configuration parameter of the full range spiral scanning strategy;

[0075] Fig.16 It is a simulation comparison diagram of equal linear speed under different configuration parameters of the full range spiral scanning strategy;

[0076] Figure 17-Figure 18 This is a simulation comparison chart of equal linear speed under the addition of spot radius for the full range spiral scanning strategy;

[0077] Fig.19 It is the first starting point position diagram of the skip scanning fast reflection mirror;

[0078] Figure 20-22 Schematic diagram of calculating the delay time through a two-step control algorithm. DETAILED DESCRIPTION

[0079] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0080] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0081] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0082] See also Figure 1 and Figure 2 The present invention provides a system for tracking and aiming laser using an optical fiber power meter, comprising a quick-reflection mirror (1), the mirror surface of the quick-reflection mirror (1) reflects incident laser light to an optical fiber, an optical fiber power meter (2) is provided on the optical fiber, the optical fiber power meter (2) is connected to a tracking and aiming module (3), and the tracking and aiming module (3) is connected to a driving circuit (4) of the quick-reflection mirror (1);

[0083] The optical fiber power meter (2) is used to detect the optical signal incident on the optical fiber to obtain the magnitude of the power detection signal;

[0084] The tracking module (3) is used to: process the power detection signal to obtain a power detection value and select a corresponding scanning strategy, and generate a driving control signal in executing the scanning strategy to find the best optical fiber coupling point;

[0085] The driving circuit (4) drives the fast reflection mirror (1) to adjust its position according to the driving control signal, so that the mirror surface of the fast reflection mirror (1) points to the optimal optical fiber coupling point.

[0086] Since the algorithm eliminates the beam splitter and position detection device, the incident light source can be coupled into the optical fiber at full power after being reflected by the fast mirror, reducing the optical power loss caused by beam splitting detection.

[0087] The present invention directly sets a fiber optic power meter on the optical fiber receiving the laser, thereby aiming according to the detection signal fed back by the fiber optic power meter and the scanning strategy, eliminating the position detection device and the spectroscope, reducing the cost, reducing the difficulty of installation and adjustment, and saving installation space.

[0088] Specifically, the fast reflex mirror of the present invention is a MEMS fast reflex mirror, which utilizes the high bandwidth and high-precision pointing control of the MEMS fast reflex mirror and the feedback of the optical fiber power meter to realize steady-state communication. By quickly and accurately controlling the pointing direction of the light beam and real-time monitoring the power of the received optical signal, the stability and accuracy of the communication can be ensured. The MEMS fast reflex mirror is used to accurately control the pointing direction of the light beam and realize high-speed and high-precision transmission of the optical signal. It has the advantages of small size, light weight, low power consumption, fast response speed and high control accuracy. It utilizes micro-electromechanical system (MEMS) technology to change the optical path through a tiny mechanical structure to realize precise pointing control of the light beam. Specifically, the fast reflex mirror can be other types of fast reflex mirrors.

[0089] Specifically, the fiber optic power meter is used to monitor the power of the optical signal in real time to ensure the stability and accuracy of the optical signal. It has the characteristics of high precision, high stability and wide measurement range. Through the built-in sensor and circuit, the optical signal is converted into an electrical signal, and amplified, filtered and digitized to finally obtain the power detection signal output of the laser signal. The power detection signal is used for subsequent tracking and aiming algorithm processing. Specifically, the fiber optic power meter is, for example, a photodiode.

[0090] The tracking and aiming module and the quick-reflecting mirror of the present invention are arranged in the optical machine, and the optical machine is also used to converge the laser light emitted by the laser to form a laser spot, which is then reflected to the optical fiber by the mirror surface of the quick-reflecting mirror. After the light receiving hole of the optical fiber receives the spot, the optical signal inside the optical fiber is still transmitted. The optical fiber power meter will convert the optical signal of the optical fiber into a weak current signal, and then rely on the rear-end amplification circuit to convert the current signal into voltage while also amplifying the signal power. The analog voltage signal can be converted from analog quantity to digital quantity through ADC (Analog-to-Digital Converter). The final optical power will correspond to a digital quantity in the range of 0 to 65535.

[0091] The MEMS fast mirror can be understood as a reflector that can be deflected, changing the reflection direction of light through mechanical deflection. In theory, only light with one incident angle can completely enter the light receiving hole. If the incident angle is slightly deflected, part of the light cannot enter the light receiving hole and will be lost in natural transmission, causing the optical power received by the optical fiber to decrease.

[0092] The goal of the tracking module of the present invention is to locate the position where the optical fiber receives the maximum optical power by controlling the deflection angle of the fast-reflection mirror. Because the tracking target, such as the offset of the optical fiber, will cause the deflection angle of the fast-reflection mirror corresponding to the previous maximum received power to change, it is necessary to continuously adjust the angle of the maximum received power. This process is tracking. The concept of conditional update is that if the optical power returned by the optical power meter at the current moment is greater than the historical maximum value, this optical power value is defined as the retained maximum power, and the principle of gradual approximation is used to locate the maximum optical power value.

[0093] See also Figure 3 Furthermore, the tracking module (3) includes:

[0094] A first scanning submodule (31) is used to acquire the position of a fast reflection mirror whose power detection value is greater than a first threshold value based on a full-range spiral scanning strategy, and form a first acquisition result;

[0095] A second scanning submodule (32) is connected to the first scanning submodule (31) and is used to obtain the position of the fast reflection mirror having a power detection value greater than a second threshold value based on a mid-range circular scanning strategy according to the position of the fast reflection mirror of the power detection value in the first acquisition result, thereby forming a second acquisition result;

[0096] The third scanning submodule (33) is respectively connected to the second scanning submodule (32) and the first scanning submodule (31), and is used to obtain the optimal optical fiber coupling point based on the optimal approach range scanning strategy according to the position of the fast reflection mirror of the power detection value obtained in the second acquisition result.

[0097] Since the movement of the MEMS fast-reflecting mirror actually carries deflection angles in two directions, X and Y, namely the two vectors of pitch and roll, the corresponding ones in the plane coordinates are (X, Y).

[0098] The core of the present invention is based on the application of spiral scanning algorithm and two-step control algorithm. The spiral scanning algorithm will calculate the pointing vector target of the fast reflex mirror at each moment as the input target displacement of the system. The two-step control algorithm is an algorithm for controlling the fast reflex mirror to achieve high bandwidth and high precision pointing, and will also convert the vector into a target digital quantity. After the first-level digital / analog conversion, the output voltage value is converted into a high voltage value after the driving circuit to power the fast reflex mirror, thereby generating an actual displacement, that is, the deflection of the fast reflex mirror.

[0099] When the mirror is deflected, the direction of the incident laser is changed at the same time, and the sampling signal is triggered at this time. The fiber optic power meter starts to collect the power value of the fiber coupling at the current moment. The power value at this moment is a weak current signal. After the amplification circuit, the current signal is converted into a larger voltage signal. After entering the first-level analog / digital conversion, a digital value representing the optical power is generated. Each optical power value at the current moment will be compared with the maximum power value at the previous moment to determine whether the current direction of the fast-reflecting mirror is the best coupling point, that is, the optical power value coupled into the optical fiber is the largest. The difference after comparison is used as feedback information to realize the closed loop of control.

[0100] The spiral scanning algorithm generally utilizes the mutual conversion and coordination of polar coordinates and rectangular coordinates to realize the calculation of the control trajectory.

[0101] The equation for a typical Archimedean screw in polar coordinates is:

[0102] R=a+b*θ

[0103] Among them, R is the radius, θ is the angle, b is the pitch value, the radius R increases linearly with the angle θ, and a is a constant.

[0104] Fig.12 The simulation diagram of spiral scanning with constant angular velocity is shown under the conditions of configuration parameters pitch b=10, control speed (1 / frequency), constant angular velocity speed=2, and number of cycles cycle=3.

[0105] Fig.13 The simulation diagram of spiral scanning with constant angular velocity is shown under the configuration parameters of pitch b=10, constant angular velocity speed=3, and number of cycles=3.

[0106] Fig.14 The simulation diagram of spiral scanning with constant angular velocity is shown under the configuration parameters of pitch b=10, constant angular velocity speed=4, and number of cycles=3.

[0107] Due to the constant angular velocity spiral, the spiral line has a higher linear velocity as it goes to the outer circle during scanning. When the straight-line distance between two target positions is greater than the laser spot size, a large number of missed scans will occur. In order to solve the above problem, the present invention solves the missed scan problem by using a constant linear velocity spiral scanning algorithm.

[0108] Below is the solution equation for analyzing the equidistant spiral at constant linear speed.

[0109] Approximately consider a small section of the spiral as a part of the circle and intercept an arc of length L, then:

[0110] L=speed*t

[0111] In the above formula, t is the unit time, the default value is 1 during simulation, and speed here is the linear speed.

[0112] Calculate the angle corresponding to L: Δθ, the formula is as follows:

[0113] Δθ*R=Δθ*(a+b*∑θ)

[0114] Δθ*R=Δθ*(a+b*∑θ)=L=speed*t

[0115] At this time, a=0, t=1, Δθ=∑θ, then:

[0116] Δθ=sqrt(speed / b)

[0117] Let Δθ be θ1, and repeat the above steps to calculate the new Δθ:

[0118] Δθ*R=Δθ*(a+b*∑θ)=L=speed*t

[0119] have to:

[0120] Δθ*(θ1+Δθ)=speed / b

[0121] There is a quadratic equation that can be solved to get Δθ, and so on:

[0122]

[0123] Fig.15 The simulation diagram of spiral scanning with constant linear speed is shown under the conditions of configuration parameters a=0, pitch b=20 / 2π, constant linear speed speed=5, and number of cycles cycle=3.

[0124] Fig.16 The simulation diagram of spiral scanning with constant linear speed under different configuration parameters of pitch b and constant linear speed number of cycles is shown.

[0125] Introducing parameter R b eamspot represents the radius of the light spot, and substitutes it into the spiral scan, taking R b eamspot =2 and R b eamspot =5 for comparison,

[0126] Fig.17 Demonstrated the introduction of R b eamspot =2 spiral scanning simulation diagram of equal linear velocity.

[0127] Fig.18 Demonstrated the introduction of R b eamspot =5 spiral scanning simulation diagram of equal linear velocity.

[0128] Figure 12-Figure 18 The horizontal axis is the X axis and the vertical axis is the Y axis.

[0129] See also Figure 4 , further, the first scanning submodule (31) comprises:

[0130] A starting point updating unit (311) is used to update the first starting point position of the fast reflection mirror as the starting point for executing the full range spiral scanning strategy;

[0131] A first scanning unit (312), connected to the starting point updating unit (311), is used to start executing a full-range spiral scanning strategy based on the first starting point position as the starting point;

[0132] A first judgment unit (313) is connected to the starting point updating unit (311) and the first scanning unit (312) respectively, and is used to judge whether there is a power detection value greater than a first threshold value when the fast reflection mirror is at the first starting point position and executes the full-range spiral scanning strategy, and obtain a first judgment result;

[0133] The first scanning unit (312) is used for:

[0134] When the first judgment result is that there is a power detection value greater than the first threshold, stop executing the full-range spiral scanning strategy, form a first acquisition result and output it to the second scanning submodule;

[0135] When the first judgment result after executing a full-range spiral scanning strategy is that there is no power detection value greater than the first threshold, a first error reporting information is generated;

[0136] The starting point updating unit (311) is also used to update the first starting point position of the quick reflection mirror according to the first error reporting information, as the starting point for the next execution of the full-range spiral scanning strategy.

[0137] Specifically, the first scanning submodule (31) further includes an initialization unit (30), which is used to enter scanning configuration parameters and initialize scanning time when tracking and aiming is enabled;

[0138] The starting point updating unit (311) is connected to the initialization unit (30) and is used to update the first starting point position of the fast reflection mirror after the initialization unit performs scanning configuration parameter entry and initialization scanning time.

[0139] Specifically, the tracking and aiming module (3) further comprises a preprocessing module (34), which is respectively connected to the first scanning submodule (31), the second scanning submodule (32) and the third scanning submodule (33) and is used for acquiring a compensation model and preprocessing a power detection signal collected by the optical fiber power meter to obtain a power detection value, wherein the preprocessing comprises compensating the power detection signal using the compensation model, and obtaining the power detection value after the preprocessing.

[0140] The compensation data includes background light compensation data, temperature compensation data and ground signal compensation data.

[0141] Specifically, the system is provided with a laser protection cover. When the laser protection cover is opened and the emitted laser is covered, the optical fiber power meter collects the ambient light detection signal, and the preprocessing module (34) processes the ambient light detection signal to obtain background light compensation data and saves it.

[0142] The preprocessing module (34) forms and stores ground signal compensation data according to the ground signal value obtained by sampling.

[0143] The preprocessing module (34) processes the ambient temperature signal to obtain temperature compensation data.

[0144] During the tracking process, the preprocessing module (34) collects the power detection signal obtained by the optical fiber power meter and compensates it in sequence using the background light compensation data, the ground signal compensation data and the temperature compensation data to obtain a power detection value.

[0145] The SPI communication protocol is used to collect optical fiber detection signals. When wire crosstalk or spatial radiation interference affects SPI communication, it will cause signal jumps. Since SPI is not a differential signal and does not have good anti-interference ability, ground signal compensation can reduce the uniform value jump caused by interference to a certain extent.

[0146] The main factors that cause the sampling value of the fiber optic power meter to change due to temperature are the following two points: the change in the photoelectric conversion coefficient and the change in the performance of the electronic device. In a constant temperature environment, the sampling value of the fiber optic power meter does not need to consider the influence of temperature, but when the ambient temperature changes beyond a temperature threshold, the sampling value of the fiber optic power meter becomes unreliable. Due to the randomness of the electronic devices in each fiber optic power meter, the temperature compensation model needs to be established based on each fiber optic power meter through experiments.

[0147] The main purpose of the full-range spiral scanning strategy is to search for the light spot. Given a vague azimuth pointing, a matching coupling threshold, i.e., the first threshold, will be set. After each scanning point is in place, the current power detection value will be compared with the first threshold to determine whether there is coupling power. If there is no coupling power (i.e., not greater than the first threshold), the displacement of the next scanning point will be executed until a full-range scan is completed. If there is no coupling power during the entire scanning process, an error will be reported (forming the first error reporting information), and then a jump step will be executed, switching to another initial scanning point and using this scanning point as the first starting point to start a full-range spiral scanning process again. The full-range spiral scan will be based on a first starting point position and the coordinate system will be offset around this point. The rules for jump step scanning are as follows: Fig.19 As shown, Fig.19 The upper left corner is the first starting point position. According to the rule of scanning the column first and then the row, the first starting point position of each spiral scan is updated from left to right and from top to bottom.

[0148] See also Figure 5 , further, the second scanning submodule (32) comprises:

[0149] A second scanning unit (321) is used to use the position of the fast reflection mirror of the power detection value obtained in the first acquisition result as the second starting point position to execute a medium-range circular scanning strategy;

[0150] A second judgment unit (322) is connected to the second scanning unit (321) and is used to: judge whether the power detection value of the fast reflection mirror at the second starting point position and the circular scanning strategy in the executed range have a power detection value greater than a second threshold value, and obtain a second judgment result;

[0151] The second scanning unit (321) is also used for:

[0152] When the second judgment result is that there is a power detection value greater than the second threshold, stop executing the circular scanning strategy in the middle range, form a second acquisition result and output it to the third scanning submodule;

[0153] After executing a cycle of the mid-range circular scanning strategy, when no second judgment result has a power detection value greater than the second threshold, second error reporting information is generated.

[0154] When there is a power detection value exceeding the first threshold value in the full-range spiral scan, the fast mirror will immediately stop the full-range spiral scan and quickly point to the position, and use it as a new scanning starting point to start the mid-range circular scan. The purpose at this time is to approach the clear position from the vague position to the actual communication position. The mid-range circular scan will expand from the inside to the outside, each time with a fixed scanning starting point as the center of the circle, and an integer multiple of the spot radius as the continuously iterated scanning radius. The initial interval of 45° is used as the vector angle. When a complete single circle is scanned, each time a single circle is scanned, the power detection value of the single circle scanning point and the center point of the circle are compared, and the maximum power detection value is retained. The fast mirror points to the point with the maximum power detection value, and then determines the center of the next round of single circle scanning in a scanning cycle to continue the circular scan. If there is a power detection value greater than the second threshold value in the scan, it indicates that the current position pointed by the fast mirror meets the communication power standard, and the best approach range scanning strategy is continued to obtain the best fiber coupling point. If the power detection values ​​in the mid-range circular scan of a cycle are not greater than the second threshold, it indicates that the communication standard has not been met, and a second error reporting message is generated. According to the second error reporting message, the first scanning submodule updates the first starting point position, for example Fig.19 In this way, the full-range spiral scanning strategy is continued. In addition, before entering the full-range spiral scanning strategy, a compensation data update is performed.

[0155] See also Figure 6 , further, the third scanning submodule (33) comprises:

[0156] A third scanning unit (331) is used to use the position of the fast reflection mirror of the power detection value obtained in the second acquisition result as the third starting point position, execute the best approach range scanning strategy, and obtain the best optical fiber coupling point;

[0157] A third judgment unit (332), connected to the third scanning unit (331), is used to judge whether the detected power detection value drops to a value not greater than a first threshold value when the fast reflection mirror points to the optimal optical fiber coupling point, and obtain a third judgment result;

[0158] The third scanning unit (331) is further used for:

[0159] When the third judgment result is that the power detection value is not greater than the first threshold, third error reporting information is generated;

[0160] When the third judgment result is that the power detection value is greater than the first threshold, the best approach range scanning strategy continues to be executed.

[0161] The optimal approach range spiral scanning strategy refers to the method of continuously searching for the optimal fiber coupling point when the coupling power has met the power requirement of communication (greater than the second threshold). The main reasons are: 1. To find the optimal coupling position of the fast mirror in order to reduce the bit error rate during communication; 2. There will be unpredictable random interferences such as vibration and atmospheric turbulence during communication, which will affect the stability of communication, and it is necessary to dynamically adjust the fast mirror command to suppress the disturbance.

[0162] The strategy of spiral scanning in the best approximation range is a pseudo-random probability control method. If 360° is divided into equal parts at 45° angles, a total of 8 vector units can be divided. The concept of the best approximation is to generate one of the 8 vectors in turn according to the set number of sample sets and the principle of maximum probability as the target quantity for the next moment to move, and also move in a circular manner, while comparing the power detection values ​​of the current scanning point and the previous scanning point. If the power detection value of the current scanning point is larger, the current scanning initial point is used as the center of the circle to scan in a circular manner. If the power detection value of the current scanning point is smaller, the existing scanning state is maintained and the scanning continues. If no iteration is performed after the 8 vector movements on the circle are completed, it is considered that the current light spot is already at the best fiber coupling point (i.e., the center position of the circle). Specifically, the scanning strategy executed by the present invention is in a static state after reaching the best fiber coupling point, and there is no need to maintain the dynamic characteristics of the position at all times like other controls. The control algorithm of the present invention can be in a static state when the best coupling position is reached, and there is no need to control the dynamic characteristics of the position at all times.

[0163] During the execution of the optimal approach range spiral scanning strategy and when the fast mirror is at the optimal fiber coupling point, the third judgment unit (332) still detects whether the power detection value obtained in real time by the fiber power meter is greater than the first threshold value. If it is greater than the first threshold value, it indicates that the light spot is currently captured, but the power detection value decreases, indicating that the light spot is offset in a small range, and the optimal approach range scanning strategy is continued to be executed. The optimal approach range scanning strategy is: if the power detection value is detected to rise, the starting point of the fast mirror is updated to a position with a higher power detection value, and the point scanning and power detection value comparison are continued on the circumference of a fixed radius with the starting point as the center of the circle. If the power detection value is not detected to rise, the circumference of the circle with the current starting point of the fast mirror as the center of the circle is scanned. If the points on the circumference are scanned and the power value detected at the center of the circle is the largest, it is considered to be the optimal fiber coupling point. If the power detection value at the optimal fiber coupling point is detected to be lower than the first threshold value, it is considered that the light spot is offset due to the shaking of the optical fiber, etc., and the target is not detected. At this time, an error report is made, and the full-range spiral scanning strategy is started again to roughly locate the light spot.

[0164] See also Figure 20-22 In the execution process of the full-range spiral scanning strategy, the mid-range circular scanning strategy and the best approach range scanning strategy, when generating a driving control signal to control the quick mirror to move to the next position, a two-step control algorithm is used to send two control instructions to the driving circuit, that is, after sending a control instruction once at the first moment t0, a driving control instruction is sent again at the moment t1, and the quick mirror reaches the next position only through two control instructions. The driving voltage of each control instruction is half of the total driving voltage required for the driving circuit, and half the voltage is applied twice so that the total driving voltage is reached after two times.

[0165] The two-step control is an algorithm developed based on the resonant frequency of the MEMS fast mirror used. It achieves high-performance control of the mirror by applying the cross-resonant frequency. Compared with the traditional control scheme that is lower than the resonant frequency to avoid resonance, it can achieve ultra-high bandwidth control twice the resonant frequency without causing self-oscillation of the mirror. The two-step control algorithm is also affected by the bandwidth of the hardware and is divided into the following three cases:

[0166] When the driving establishment time t2 is less than or equal to the two-step control method interval, the control bandwidth is 1 / 2f, where f is the resonant frequency of the fast reflection mirror.

[0167] At the resonant frequency f, calculate the total delay time 1 / 2f, which is half of the resonant period.

[0168] If the hardware delay time (eg, the driving circuit voltage rise time, ie, the driving establishment time t2) is less than half of the resonance period, then t1 = t0 + t2 + Δt, where Δt is the additionally set delay time.

[0169] If the hardware delay time (ie, the drive establishment time t2) is equal to half of the resonance period, then t1 = t0 + t2, and no additional delay time is required, and only the second control instruction needs to be sent after t2.

[0170] If the hardware delay time (ie, the drive establishment time t2) is greater than half of the resonant period, it is necessary to consider replacing the device to achieve performance matching.

[0171] See also Figure 7 The present invention also provides a method for tracking and aiming laser using a fiber optic power meter, using the aforementioned system for tracking and aiming laser using a fiber optic power meter, comprising:

[0172] Step A1, the mirror surface of the fast reflection mirror reflects the incident laser to the optical fiber, and the optical fiber power meter on the optical fiber detects the optical signal incident to the optical fiber to obtain the size of the power detection signal;

[0173] Step A2, pre-processing the power detection signal to obtain a power detection value;

[0174] Step A3, selecting a corresponding scanning strategy based on the power detection value, and generating a driving control signal in executing the scanning strategy to find the best optical fiber coupling point;

[0175] Step A4, driving the fast reflection mirror to adjust its position according to the driving control signal, so that the mirror surface of the fast reflection mirror points to the optimal optical fiber coupling point.

[0176] The present invention directly sets a fiber optic power meter on the optical fiber receiving the laser, thereby aiming according to the detection signal fed back by the fiber optic power meter and the scanning strategy, eliminating the position detection device and the spectroscope, reducing the cost of use, reducing the difficulty of installation and adjustment, and saving installation space. Since the algorithm eliminates the spectroscope and the position detection device, the incident light source can be fully coupled into the optical fiber after being reflected by the fast mirror, reducing the optical power loss caused by the spectroscopic detection.

[0177] See also Figure 8 , further, step A3 comprises:

[0178] Step A31, based on a full-range spiral scanning strategy, obtaining the position of the fast reflection mirror whose power detection value is greater than a first threshold, to form a first acquisition result;

[0179] Step A32, according to the position of the fast reflection mirror of the power detection value in the first acquisition result, based on the circular scanning strategy in the middle range, the position of the fast reflection mirror with a power detection value greater than the second threshold is acquired to form a second acquisition result;

[0180] Step A33, according to the position of the fast reflection mirror of the power detection value obtained in the second acquisition result, the best fiber coupling point is obtained based on the best approach range scanning strategy.

[0181] In step A2, the processing of the power detection signal includes compensating with compensation data to obtain a power detection value. The compensation data includes background light compensation data, temperature compensation data and ground signal compensation data. The power detection signal collected by the optical fiber power meter is compensated with the background light compensation data, the ground signal compensation data and the temperature compensation data in turn to obtain a power detection value.

[0182] The background light compensation data may be acquired once before each execution of step A3, that is, once before each start of the full-range spiral scanning strategy.

[0183] See also Fig. 9 , further, step A31 includes:

[0184] Step A311, updating the starting point of the fast reflection mirror as the first starting point position for executing the full range spiral scanning strategy;

[0185] Step A312, determining whether the power detection value obtained by the fast reflection mirror at the first starting point is greater than a first threshold:

[0186] If not, execute step A313;

[0187] If yes, execute step A315;

[0188] Step A313, based on the first starting point position as the starting point, start to execute the full-range spiral scanning strategy, and determine whether there is a power detection value greater than the first threshold value in the execution of the full-range spiral scanning strategy:

[0189] If not, execute step A314;

[0190] If yes, execute step A315;

[0191] Step A314, after executing a full-range spiral scanning strategy, generating first error reporting information, and continuing to step A311;

[0192] Step A315, stop executing the full-range spiral scanning strategy, form and output the first acquisition result, and then execute step A32.

[0193] The main purpose of the full-range spiral scanning strategy is to search for the light spot. Given a vague azimuth pointing, a matching coupling threshold, namely the first threshold, will be set. After each scanning point is in place, the current power detection value will be compared with the first threshold to determine whether there is coupling power. If there is no coupling power (i.e., not greater than the first threshold), the displacement of the next scanning point will be executed until a full-range scan is completed. If there is no coupling power during the entire scanning process, an error will be reported (forming the first error reporting information), and then a jump step will be executed to switch to another initial scanning point and use this scanning point as the first starting point to start a full-range spiral scan again.

[0194] Specifically, the full-range spiral scanning strategy of the present invention adopts a spiral scanning strategy of equal linear velocity, ensuring that the distance between two adjacent points on the outer circle does not increase as much as the equal angular velocity scanning and exceed the spot size, resulting in missed scanning.

[0195] See also Fig.10 , further, step A32 includes:

[0196] Step A321, taking the position of the fast mirror of the power detection value obtained in the first acquisition result as the second starting point position, and determining whether the power detection value of the fast mirror at the second starting point position is greater than a second threshold:

[0197] If not, execute step A322;

[0198] If yes, execute step A324;

[0199] Step A322: Execute the circular scanning strategy in the middle range from the second starting point as the starting point, and determine whether there is a power detection value greater than the second threshold value in the circular scanning strategy in the middle range:

[0200] If not, execute step A323;

[0201] If yes, execute step A324;

[0202] Step A323, after executing a cycle of the mid-range circular scanning strategy, second error reporting information is generated, and then step A31 is executed;

[0203] Step A324, stop executing the circular scanning strategy in the middle range, form and output the second acquisition result, and then execute step A33.

[0204] When there is a power detection value exceeding the first threshold value during the full-range spiral scan, the fast reflex mirror will immediately stop the full-range spiral scan and quickly point to the position, and use this as the new scanning starting point to start the mid-range circular scan. The purpose at this time is to approach from the vague position to the clear position that can actually communicate. If there is a power detection value greater than the second threshold value during the scan, it indicates that the current position pointed by the fast reflex mirror meets the communication power standard, and the best approximation range scanning strategy is continued to obtain the best fiber coupling point. If there is no power detection value that is not greater than the second threshold value in a cycle of the mid-range circular scan, it indicates that the communication standard has not yet been met, and a second error reporting information is generated. According to the second error reporting information, the first starting point position will be updated, for example, Fig.19 In that case, the full-range spiral scanning strategy is continued for a rough search. Also, before entering the full-range spiral scanning strategy, the compensation data is updated once.

[0205] See also Fig.11 , further, step A33 includes:

[0206] Step A331, taking the position of the fast reflection mirror of the power detection value obtained in the second acquisition result as the third starting point position, executing the best approach range scanning strategy to find the best fiber coupling point;

[0207] Step A332, when the fast reflection mirror points to the best fiber coupling point, if it is detected that the power detection value decreases but is greater than the first threshold, continue to execute the best approach range scanning strategy; if it is detected that the power detection value decreases and is not greater than the first threshold, execute step A333;

[0208] Step A333, forming third error reporting information, and then executing step A31.

[0209] The optimal approach range spiral scanning strategy refers to a method of continuously searching for the optimal fiber coupling point even when the coupling power has met the communication power requirement (greater than the second threshold). The control algorithm of the present invention can be static when the optimal coupling position is reached, and there is no need to control the dynamic characteristics of the position at all times.

[0210] During the execution of the optimal approach range spiral scanning strategy and when the fast mirror is at the optimal fiber coupling point, it is still detected whether the power detection value obtained in real time by the fiber power meter is greater than the first threshold. If it is greater than the first threshold, it indicates that the light spot is currently captured, but the power detection value decreases, indicating that the light spot is offset in a small range, and the optimal approach range scanning strategy is continued. The optimal approach range scanning strategy is: if the power detection value is detected to rise, the starting point of the fast mirror is updated to a position with a higher power detection value, and the point scanning and power detection value comparison are continued on the circumference of the fixed radius with the starting point as the center. If the power detection value is not detected to rise, the circumference of the circle with the current starting point of the fast mirror as the center is scanned. If the points on the circumference complete the scanning and the power value detected at the center of the circle is the largest, it is considered to be the optimal fiber coupling point. If the power detection value at the optimal fiber coupling point is detected to be lower than the first threshold, it is considered that the light spot is offset in a large range due to the shaking of the optical fiber, and the target has not been detected, an error report is made, and the full-range spiral scanning strategy is started again to roughly locate the light spot.

[0211] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for laser tracking and aiming using an optical fiber power meter, characterized in that: It includes a quick-reflection mirror, the mirror surface of which reflects the incident laser to the optical fiber, the optical fiber is provided with an optical fiber power meter, the optical fiber power meter is connected to the tracking and aiming module, and the tracking and aiming module is connected to the driving circuit of the quick-reflection mirror; The optical fiber power meter is used to detect the optical signal incident on the optical fiber to obtain the size of the power detection signal; The tracking module is used to: pre-process the power detection signal to obtain a power detection value and select a corresponding scanning strategy, and generate a driving control signal in executing the scanning strategy to find the best optical fiber coupling point; The driving circuit drives the fast reflection mirror to adjust its position according to the driving control signal, so that the mirror surface of the fast reflection mirror points to the optimal optical fiber coupling point.

2. A system for laser tracking and aiming using an optical fiber power meter as claimed in claim 1, characterized in that: The tracking and aiming module comprises: A first scanning submodule, configured to acquire the position of the fast reflection mirror having the power detection value greater than a first threshold value based on a full-range spiral scanning strategy, and form a first acquisition result; A second scanning submodule, connected to the first scanning submodule, is used to obtain the position of the fast reflection mirror whose power detection value is greater than a second threshold value based on a mid-range circular scanning strategy according to the position of the fast reflection mirror of the power detection value in the first acquisition result, to form a second acquisition result; The third scanning submodule is connected to the second scanning submodule and the first scanning submodule respectively, and is used to: obtain the optimal fiber coupling point based on the optimal approach range scanning strategy according to the position of the fast reflection mirror of the power detection value obtained in the second acquisition result.

3. A system for laser tracking and aiming using an optical fiber power meter as claimed in claim 2, characterized in that: The first scanning submodule comprises: A starting point updating unit, used for updating the first starting point position of the fast reflection mirror as the starting point for executing the full range spiral scanning strategy; A first scanning unit, connected to the starting point updating unit, is used to start executing a full-range spiral scanning strategy based on the first starting point position as the starting point; A first judgment unit, connected to the starting point updating unit and the first scanning unit, respectively, for judging whether the power detection value of the fast reflection mirror is greater than a first threshold value when the fast reflection mirror is at the first starting point and executing the full-range spiral scanning strategy, and obtaining a first judgment result; The first scanning unit is used for: When the first judgment result is that there is a power detection value greater than the first threshold, stop executing the full-range spiral scanning strategy, form the first acquisition result and output it to the second scanning submodule; When the first judgment result after executing the full-range spiral scanning strategy once is that there is no power detection value greater than the first threshold, generating first error reporting information; The starting point updating unit is further used for updating the first starting point position of the fast reflection mirror according to the first error reporting information as the starting point for the next execution of the full-range spiral scanning strategy.

4. A system for laser tracking and aiming using an optical fiber power meter as claimed in claim 2, characterized in that: The second scanning submodule comprises: A second scanning unit, configured to use the position of the fast reflection mirror of the power detection value obtained in the first acquisition result as a second starting point position, and execute a medium-range circular scanning strategy; A second judgment unit, connected to the second scanning unit, is used to: judge the power detection value of the fast reflection mirror at the second starting point and whether the power detection value is greater than the second threshold value in the execution of the circular scanning strategy in the middle range, and obtain a second judgment result; The second scanning unit is further used for: When the second judgment result is that there is a power detection value greater than the second threshold, stop executing the circular scanning strategy in the middle range, form the second acquisition result and output it to the third scanning submodule; After executing the circular scanning strategy in the middle range for one cycle, when none of the second judgment results has a power detection value greater than the second threshold, second error reporting information is generated.

5. A system for laser tracking and aiming using a fiber optic power meter as claimed in claim 2, characterized in that: The third scanning submodule comprises: A third scanning unit, configured to use the position of the fast reflection mirror of the power detection value obtained in the second acquisition result as a third starting point position, execute an optimal approach range scanning strategy, and obtain the optimal fiber coupling point; a third judgment unit, connected to the third scanning unit, and configured to judge whether the detected power detection value drops to a value not greater than the first threshold value when the fast reflection mirror points to the optimal optical fiber coupling point, so as to obtain a third judgment result; The third scanning unit is also used for: When the third judgment result is that the power detection value is not greater than the first threshold, generating third error reporting information; When the third judgment result is that the power detection value is greater than the first threshold, the optimal approach range scanning strategy continues to be executed.

6. A method for laser tracking using an optical fiber power meter, characterized in that: A system for laser tracking and aiming using a fiber optic power meter as described in any one of claims 1 to 5, comprising: Step A1, the mirror surface of the fast reflection mirror reflects the incident laser to the optical fiber, and the optical fiber power meter on the optical fiber detects the optical signal incident to the optical fiber to obtain the size of the power detection signal; Step A2, preprocessing the power detection signal to obtain a power detection value; Step A3, selecting a corresponding scanning strategy based on the power detection value, and generating a driving control signal in executing the scanning strategy to find the optimal optical fiber coupling point; Step A4, driving the fast reflection mirror to adjust its position according to the driving control signal, so that the mirror surface of the fast reflection mirror points to the optimal optical fiber coupling point.

7. A method for laser tracking and aiming using a fiber optic power meter as claimed in claim 6, characterized in that: The step A3 comprises: Step A31, based on a full-range spiral scanning strategy, obtaining the position of the fast reflection mirror where the power detection value is greater than a first threshold, to form a first acquisition result; Step A32, according to the position of the fast reflection mirror of the power detection value in the first acquisition result, based on the circular scanning strategy in the middle range, the position of the fast reflection mirror where the power detection value is greater than a second threshold is acquired to form a second acquisition result; Step A33, acquiring the optimal fiber coupling point based on the optimal approach range scanning strategy according to the position of the fast reflection mirror of the power detection value acquired in the second acquisition result.

8. A method for laser tracking and aiming using a fiber optic power meter as claimed in claim 7, characterized in that: The step A31 comprises: Step A311, updating the starting point of the fast reflection mirror as the first starting point position for executing the full range spiral scanning strategy; Step A312, determining whether the power detection value obtained by the fast reflection mirror at the first starting point is greater than a first threshold: If not, execute step A313; If yes, execute step A315; Step A313, based on the first starting point position as the starting point, start to execute the full-range spiral scanning strategy, and determine whether there is a power detection value greater than the first threshold value in the execution of the full-range spiral scanning strategy: If not, execute step A314; If yes, execute step A315; Step A314, after executing the full-range spiral scanning strategy once, generating first error reporting information, and continuing to step A311; Step A315, stop executing the full-range spiral scanning strategy, form and output the first acquisition result, and then execute the step A32.

9. A method for laser tracking and aiming using a fiber optic power meter as claimed in claim 7, characterized in that: The step A32 comprises: Step A321, taking the position of the quick-reflection mirror of the power detection value obtained in the first acquisition result as the second starting point position, and determining whether the power detection value of the quick-reflection mirror at the second starting point position is greater than the second threshold: If not, execute step A322; If yes, execute step A324; Step A322: Execute the medium-range circular scanning strategy from the second starting point as the starting point, and determine whether there is a power detection value greater than the second threshold value during the execution of the medium-range circular scanning strategy: If not, execute step A323; If yes, execute step A324; Step A323, after executing the circular scanning strategy in the middle range for one cycle, generating second error reporting information, and then executing the step A31; Step A324, stop executing the medium-range circular scanning strategy, form and output the second acquisition result, and then execute the step A33.

10. A method for laser tracking and aiming using a fiber optic power meter as claimed in claim 9, characterized in that: The step A33 comprises: Step A331, taking the position of the fast mirror of the power detection value obtained in the second acquisition result as the third starting point position, executing the best approach range scanning strategy to find the best fiber coupling point; Step A332, when the fast mirror points to the best fiber coupling point, if it is detected that the power detection value decreases but is greater than the first threshold, continue to execute the best approach range scanning strategy, if it is detected that the power detection value decreases and is not greater than the first threshold, then execute step A333; Step A333, forming third error reporting information, and then executing the step A31.

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